Brazing is a commonly used fabrication method for producing complex aluminum articles. Brazing sheet is often used and consists of an aluminum alloy core having a high melting point and a layer of lower melting point aluminum alloy on at least one surface of the core. When this composite sheet is heated to brazing temperatures, the surface alloy melts and flows into joints as a result of capillary action. For proper functioning the melting of the surface alloy must occur at a temperature where the core alloy possesses adequate creep strength so as to resist deformation and distortion. In conventional composite brazing sheet materials the temperature difference between the melting point of the surface alloy and softening point of the core alloy is so small that it is difficult to control the brazing temperature to a close enough tolerance so that the surface alloy is melted and the core alloy is not distorted. Commonly used core alloys include Aluminum Association Alloy 3003 and Aluminum Association Alloy 6951. Aluminum Association Alloy 6951 is a heat treatable alloy and therefore requires careful temperature control and cooling control after the brazing cycle. Alloy 6951 also tends to sag excessively when subjected to brazing temperatures greater than 1100.degree. F. Most users prefer Aluminum Association Alloy 3003 as a core alloy since it is more resistant to sagging and deformation than is Aluminum Association Alloy 6951. However, even Alloy 3003 tends to sag when subjected to temperatures greater than 1100.degree. F. The mechanical properties of Alloy 3003 after brazing is completed are generally not good enough for applications subjected to high stress.